Rod packing for shock absorbers



Nov. 6, 1951 M. FUNKHOUSER ROD PACKING FOR SHOCK ABSORBERS Filed March 17, 1948 uzi IN VEN TOR.

f 0 me 0 fi/W I m m r R. 7 m ,4 w v/ 5 Patented Nov. 6, 1951 ROD PACKING FOR SHOCK ABSORBERS Mearick Funkhouser, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich., a

corporation of Delaware Application March 17, 1948, Serial No. 15,295

2 Claims.

This invention relates to improvements in hydraulic shock absorber of the direct acting type.

It is among the objects of the present invention to provide a direct acting, hydraulic shock absorber of simple structure and design in which the various tubular elements, one surrounded by another, are rigidly held against relative radial movement, thereby maintaining concentricity between all of the tubes and their respective parts and the rod of the piston which reciprocates within the innermost tube or cylinder.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. l is a side view of the shock absorber built according to the present invention, one half of the shock absorber being shown in elevation, the other half in section.

Fig. 2 is a fragmentary sectional view of a portion of the shock absorber shown in Fig. 1, one element thereof, however, being omitted.

Fig. 3 is a detail view of the rod guide in one end of the cylinder.

Referring to the drawings, the numeral 28 designates the tubular casing of the shock absorber, closed at one end by the closure member 2| which has a member 22 attached thereto for purposes of securing this portion of the shock absorber to one of the two relatively movable members whose movement is to be controlled. Spaced radial ribs 23 are provided within the closure member 2|.

. Another tubular member termed the cylinder 25, has an end member 25 which rests upon the radial ribs 23 of the casing closure member 2|. Cylinder 25 is of such a diameter that an annular space 21 is formed between it and the casing said space being termed the fluid reservoir. The cylinder end member 26 has two valves 30 and 3|. Valve 30 normally prevents the flow of fiuid from the cylinder into the reservoir but is operative to permit fluid to fiow from the reservoir 21 into the cylinder. Valve 3|, on the other hand, prevents fluid from flowing from the reservoir into the cylinder, but is operative to establish a restricted flow of fluid from the cylinder into the reservoir. As shown in Fig 1, when the end member 26 of cylinder 25 rests upon the closure member 2| of the casing 20, the opposite, outer end of the cylinder falls beneath the level of the adjacent, outer end of casing 20.

A piston 35 having a rod 38 attached thereto, is reciprocative in the cylinder 25. Rod 36 extends centrally of the cylinder and beyond the outer end of the casing 20. The piston 35 has two sets of through passages 31 and 38, providing for the transfer of fluid from one side of the piston to the other as said piston is reciprocated. Valve 39 normally closes passages 37 to prevent fluid flow therethrough When'the piston 35 moves upwardly, away from the closure member 26 of the cylinder. During this movement of the piston 35, valve ill, which normally closes passages 38 is operative to permit a restricted flow through the piston into the working chamber AI beneath the piston. However, when the movement of the piston is reversed, that is, when the piston is moved downwardly, toward the closure member 26, then valve 39 is operative to permit a fiow of fluid from chamber 4| through the piston, while valve 40 closes passages 38. Thus fluid flow through the piston in both directions is predeterminately controlled.

As stated heretofore, it is among the objects of the present invention to secure certain of the elements of the shock absorber rigidly one to another in order to prevent any radial movement or displacement therebetween. This is accomplished by constructing the shock absorber in the following manner.

A rod guide 52 forms a closure member for the upper end of the cylinder 25, or more specifically the end of the cylinder opposite the closure member 25. This rod guide is in the form of a plug having a reduced diameter portion 5| which telescopically fits into the cylinder, the shoulder 52 formed by said reduced portion, engages and rests upon the outer annular edge of the cylinder as shown in Figs. 1 and 2. [m annular groove 53 is provided in the peripheral surface of the reduced diameter portion 5| adjacent this shoulder 52. The rod guide 53 has a central opening 54, concentric with the outer peripheral surfaces of both the main body portion and the reduced diameter portion iii of the guide, the piston rod 36 being slidably supported in this opening.

The end of the rod guide 50, outside the cylinder 25 is recessed as at 55 making the guide cup-shaped to provide an outer chamber 56 surrounded by the annular wall 51. A hole 58 in the wall 51 connects the outside or the guide wall 5'! with the annular groove 53 and also with the chamber 56. Shallow grooves 59 sometimes more in the form of scratches in the outer peripheral 3 surface of the reduced diameter portion 5| of the rod guide, cooperate with the inner wall of the cylinder to form restricting passages connecting the chamber 60 in the cylinder between rod guide 50 and the piston 35 with the annular groove 53.

Surrounding the cylinder 25 for a portion of its length so as to form a shallow annular space 6| round said cylinder, is a baiile tube 62. This baflle tube is sufliciently long so that its lower end dips beneath the normal level of the fluid inside the reservoir space 21. An annular .baflle ring 63 is attached to the interior of the casing '20, the inner annular edge of said ring being in juxtaposition to the tube 62 so as toriorman annular. fluid restricting passage 64 between said tube 62 and ring 63.

The end of the baffle tube 62, adjacent the outer edge of the rod guide wall 51 is thickened as at 65 so that it will fit snugly about said annular wall portion 51 of the guide. This snug fit of tube portion 65 about the guide wall .51 is above the opening 58 in said guide wall so that said opening is always in communication with the annular space 6| between the cylinder and bafile tube. The end of the baffle tube =52 is flared inwardly so as to provide flange 6 which engages and rests upon the outer edge surface of the guide wall 51. Fitting about the portion 5| of the guide 50, the cylinder 25 is thus held rigidly concentric with the opening 54 in said guide and consequently with the piston rod 'slidable in said opening. Baffle tube :62 is also held rigidly :concentric with the rod 36 for said tube fits snugly about the guide wall'57.

The end of the casing 20, opposite its closure member 2|, has a cover cap secured thereto. Figs. 1 and 2 show this inverted cup-shaped, cover cap 10 fitting telescopically-within the casing. A portion of the cover capof :Fig. 1 is contoured to flt snugly about that portion nf .the bafiie tube which fits snugly about the .IOd guide wall portion 51, and also to fit upon the inwardly extending flange 66 of the baiiie-tuhe. opening H in thecover cap is coaxial of the.icap;portions which fit about the baffle tube 52 :and into the casing 20. Thus with cap '70 fitting snugly about the tube 62, which, fitting about "the rod guide, is itself rigidly held concentric of the rod guide opening 54, cap 10 and itsopening 'l:| will likewise be held rigidly concentric of said rod guide opening.

A resilient packing ring 80 surrounds zthe piston rod portion extending through the;outerschamber 55. An abutment ring plate Bl engages the :packing ring 80 and a spring '82 is interposed between said abutment ring and the bottom wall of the recess 55 in the rod guide. This spring urges the resilient packing ring 80-'into sealing engagement with the annular surface of .the piston rod, the inside of the cover cap 1j0, ,theinner.edge of the flange 66 when tube 62 is used and :the rod guide wall portion 51.

Any fluid which might leak past the :piston rod and the rod guide into chamber .55 :will not leak from said chamber excepting through opening 58 in the rod guide Wall, from wherethe'fiuid will pass through the annular space :65! between tube 62 and the cylinder to the gfluid supply in the fluid reservoir ,21. Likewise, any air-in chamber 60 of the cylinder may pass through the restricted passagesformedby rooves iarinto the annular g1'00Ve'53. through opening 58 and thence through annular space -r6l 111150513118 fluid supplywin the reservoir from where the air-,will

rise, pass through the annular space 64 between the baflie ring 63 and tube 62 to accumulate and be trapped in the upper region between the tube 62 and cover cap 10.

The piston rod 36 extending through and beyond the opening H in the cover cap 10 has a disc attached thereto and the disc 90 has a tube =81 fitting about it .and secured thereto. This tube 194 forms a guard surrounding the casing 20 for a portion of its length. A member 92 is secured to the piston rod, by means of which said rod is attachable to the other relatively movable member whose movement is to be controlled.

In the Fig. 2,-the bafile tube 62 is dispensed with and cover cap 10 is shaped to fit directly about ,the --wall portion :5 of the rod guide 50. When assembling, thecover cap is forced into the casing 20 until said cover cap rigidly clamps the cylinder assembly upon the radial ribs 23 of the closure member 2| of said casing. The cover cap is then secured to the casing, in the present showing preferably by welding.

Thus it may be seen that by the present construction the cylinder, baflle tube, cover cap and easing are all rigidly held concentric to each other and to the rod containing opening .154 in the rod guide 50 thereby preventing any relative movement radially or sidewise between the elements mentioned.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A device providing a rod guide, stuiflng box and centralizing closure member for the two concentric inner and outer tubes of a direct acting hydraulic shock absorber said device consisting of .a centrally apertured plug through which :a rod may slidably extend, said plug having one portion thereof adapted telescopically to extend into theinner tube to form a closure therefor and another cylindrical portion forming a packing box; a packing in said box encircling the rod and engaging the inner wall of the .box; a :centrally apertured cap fitting upon .the cylindrical portion of the plug said cap having a flared cylindrical skirt surrounding the said cylindrical extension and adapted to be telescopicallysecured to the outer tube to hold the inner and outer tubes in concentricity; and resilient means in the box, urging the packing into sealing engagement with the rod, the cap and the interior wall of the "box.

2. A device providing a rod guide, stufling box and centralizing closure member for the two concentric tubes of a direct acting hydraulic shock absorber, said device consisting of a centrally apertured plug through which a rod may slidably extend, said plug being adapted telescopically to fit into the inner tube to form an end closure member therefore and having a cylindrical, integral extension substantially thesame diameter as said inner tube, said extension forming a packing'box; a packing in said box, encircling the rod and engaging the inner wall of the 'box; a centrally apertured, cup-shaped cap vinvertedly resting upon the cylindrical extension of theplug, forming a closure member for the packing box, the depending annular Wall of the cap being spaced from and concentrically surrounding the said cy indrical extension, and providing means adapted telescopically to'be, attached to the outer tube to hold it concentric'of the inner-tube; and resilient means in the packing box, constantly,

urging the packing into sealing engagement with UNITED STATES PATENTS Name Date Brownell June 1, 1886 Goddu Dec. 6, 1927 Padgett Nov. 5, 1935 Padgett Sept. 21, 1937 Focht Jan. 17, 1939 Beecher Feb. 5, 1946 

